Boat stabilizer



April 17, 1962 o. H. DONNAN 3,029,767

BOAT STABILIZER Filed July 8. 1959 2 Sheets-Sheet 1 mmmn umimm ml INVENTOR Owen HDozzzzan I8 ATTORN 5' April 17, 1962 Filed July 8. 1959 O. H. DONNAN BOAT STABILIZER,

2 Sheets-Sheet 2 1 INVENTOR 32 Owen H Dorman wim /wzw ATTO EYS 3,029,767 BOAT STABILIZER Owen H. Donnnn, Bradenton, Fla, assiguor to Boat Stabilizers Inc, Sarasota, Fla., a corporation of Florida Filed July 8, 1959, Ser. No. 825,740 1 Claim. (Cl. 114-121) This invention relates to stabilizers for boats, and more particularly to boat stabilizers adapted to minimize pitching and rolling of a docked or anchored boat.

It is an object of the invention to provide an efficient and inexpensive apparatus for minimizing pitch and roll of a docked or anchored boat.

It is another object of the invention to provide a boat stabilizer which functions to apply a substantial damping force to upward movement of a portion of the boat to which the stabilizer is attached whereby the stabilizer may also function as a sea anchor.

The foregoing, and other objects, are achieved in a structure in which a horizontal shaft is coupled at its midpoint to a vertical stem which projects upwardly from one side of the shaft. A pair of semi-circular plates are located with their diametral edges extending along the shaft on opposite sides of the stem. The plates are pivotally connected to the shaft near each end of the shaft for pivotal movement relative to each other about the shaft toward and away from the stem. The hinges are constructed so that the plates may pivot freely toward the shaft, and at their minimum angular separation, the

plates abut opposite sides of the stem at a location above States atent: O

3,029,757 Patented Apr. 17, 1962 ice between the plate and arm portions of the member. A bore 24 extends through the plate portion-of each hinge member to slideably and rotatively receive shaft 12. When the hinge members are mounted upon shaft 12 which the respective arms of the hinge pair extending in opposite directions, abutment between the shoulder 22 of one hinge member and the free vertical side 26 of the opposing hinge member limits relative pivotal movement of the respective hinge members about shaft 12 to the positions shown in FIG. 3 wherein the upper surfaces 28 of the respective arms 29 are inclined upwardly and outwardly from opposite sides of shaft 12. The hinges are loosely clamped axially against the outer ends of the respective spacers 14 by a washer 30 and nut 32 threadably received on the outer ends of shaft 12.

A pair of semi-circular plates 34 are supported by I hinge assemblies 16 for pivotal movement about shaft Recesses in the diametral edges of the plates define a generally circular opening at a central location through the plates when in the last mentioned position.

Other objects and features of the invention will become apparent by reference to the following specification and to the drawings.

In the drawings:

FIG. 1 is a perspective view of a set of stabilizers embodying the invention in use;

FIG. 2 is a detail bottom plan view of a stabilizer embodying the invention;

FIG. 3 is a side elevational view of the stabilizer of FIG. 2;

FIG. 4 is a detail cross-sectional view takenon the line 4--4 of FIG. 3;

FIG. 5 is a detail cross-sectional view taken on the line 5-5 of FIG. 3;

FIG. 6 is a detail view, partially in section, of a hinge and plate assembly of the structure of FIG. 2; and

FIG. 7 is an exploded perspective view of one hinge assembly.

The stabilizer includes a vertical central stem 10 which may be conveniently formed from a length of standard pipe. A horizontal shaft 12 is mounted near the lower end of stem 10 as by fitting loosely within a diarnetral bore extending through stem 10. A pair of bushings or spacers 14 are slideably received on shaft 12 on each.

side of stem 10 and serve to locate a pair of binge assemblies designated generally 16 at positions spaced equidistant along shaft 12 from stem 10.

As best seen in FIG. 7, each hinge assembly 16 consists of a pair of like members each including an integral plate portion 18 and arm portion 20, the arm projecting from one side edge of the plate. Ann 24 is of a thickness approximately twice that of plate portion 18 and hence a shoulder 22 is formed on the inner end of arm 20 which extends along the vertical line of intersection 12 in the manner indicated in FIG. 3. Semi-circular recesses 36 project inwardly at a central location along the diametral edge 32 of each plate whereby, as best seen in FIG. 2, a generally circular central opening is defined when both plates are located in the position shown in FIG. 3. Preferably, the plates are secured to the respective arms 20 of the hinges as by screws 40 threadably received within tapped bores such as 42 in the hinge arms. Preferably, the upper surface of the plate is inclined radially inwardly of the plate as best seen in FIG. 4.

A swivel 44 is mounted at the upper end of stem 12 as by a bolt 46 passing through the stem and swivel.

In use, the stabilizer is suspended from the boat by means of a line 48 at a location clear of the bottom. As indicated in FIG. 1, preferably three stabilizers will be used, one attached to the boat at the bow while the remaining two are suspended from opposite sides of the boat approximately amidships. The suspended stabilizers hang freely from the boat and the plates 34 are gravitationally moved to their fully open position in which the cooperating abutment shoulders on the various hinges hold the plates in the position shown in FIG. 3.

Considering that stabilizer attached to the bow of the boat in FIG. 1, it is apparent that a wave tending to lift the bow of the boat will exert an upward force on the stabilizer. Because of the open position of plates 34 the stabilizer exerts a substantial resistance to this upward movement, thus damping the lifting movement of the bow. As the wave passes toward the stern of the boat, the bow drops, thus tending to lower the stabilizer. Since blades 34 may collapse upwardly quite freely, as indicated by the phantom line showing of FIG. 3, the stabilizer exerts no resistance to the downward movement to the bow of the boat. However, the weight of the stabilizer is sufficient to keep its suspending line taught and as soon as the next wave starts to lift the bow of the boat, the stabilizer blades are snapped, by the downward reaction of the water of the upper surfaces of the blades, to the extended position of FIG. 3 to again resist lifting movement of the bow.

The stabilizers attached to the opposite sides of the boat operate in the same fashion except that rolling movement of the boat in either direction is resisted.

The central opening defined by the proposed recesses 36 not only provides a passage for the flow of water during motion damping movement of the stabilizer, but also permits plates 34 to collapse more closely against the stem during lowering movement of the stabilizer. While the total area of plates 34 provides a substantial resistance against rapid elevating movement of the stabilizer through the water, the central opening permits the stabilizer to be raised with very little effort as long as it is raised at a very slow rate.

Stem 10 can likewise pivot about shaft 12 and hence the stabilizer is self-positioning to automatically resist the application of tension to line 48 regardless of whether the tension is applied in a truly vertical direction. Thus, the stabilizer can also function as a sea anchor.

While one embodiment of the invention has been described in detail, it will be apparent to those skilled in the art that the disclosed embodiment may be modified. Therefore, the foregoing description is to be considered exemplary rather than limiting, and the true scope of the invention is that defined in the following claim.

I claim:

A boat stabilizer comprising a vertical stem, an elongate horizontal shaft coupled at its mid-point to the lower end of said stem for rotation relative to said stern about the longitudinal axis of said shaft, a pair of semi-circular plates located on opposite sides of said stem with the diametral edge of each plate extending along said shaft, each of said plates having a semi-circular recess in its diametral edge whereby a general circular central Openings is defined in said plates concentric with said stern, hinge means at the outer ends of the diametral edges of said plates mounting said plates upon said shaft for free relative pivotal movement about the longitudinal axis of References Cited in the file of this patent UNITED STATES PATENTS 143,318 Beals Sept. 30, 1873 289,224 Clarke Nov. 27, 1883 497,533 Claypool May 16, 1893 1,788,490 Lewis Jan. 13, 1931 2,121,572 Polden et a1 June 21, 1938 2,170,889 Allin Aug. 29, 1939 2,491,564 Iversen Dec. 20, 1949 2,561,539 Seward July 24, 1951 2,586,003 Caslor Feb. 19, 1952 2,841,107 Scheider July 1, 1958 2,910,955 Long Nov. 3, 1959' 2,960,296 Sepp Nov. 15, 1960 

